This invention relates to the lining of sewers, water mains, culverts, tunnels, conduits, pipes, and other passageways (generically referred to herein as passages), and especially but not exclusively to the lining of underground passages. Lining in this context is intended to include both original lining and relining. It is anticipated that the process will be used mainly for the relining, particularly the relining of sewers.
As sewers and other passages age, they deteriorate in many ways. Cracks appear and joints separate. Infiltration through these cracks and joints creates external voids, accelerates structural deterioration and can overload collection systems and treatment plants. Many passages can be successfully rehabilitated using what is called the soft-lining or cured in place method. This method is illustrated in U.S. Pat. Nos. 4,009,063 and 4,064,211. Most deteriorating sewers can be rehabilitated economically in this way.
Other rehabilitation projects, particularly those involving larger passages, may require a different method, one using a hard liner inside the existing passage. Inserting a hard liner in an existing passage poses several problems. Typically, there is a limited amount of space available in such passages, so manipulating the liner to place it in the passage and/or assemble it in place can be difficult. Moreover, the lining of such passages should not excessively reduce the cross-sectional area of the passage, since otherwise the flow rate through the passage will be unduly restricted.
Hard liners typically are formed from a polymer concrete, which in turn is composed of a suitable resin and approximately 70% by weight filler (such as sand). Frequently, one or more fiberglass layers are included adjacent the inner and outer surfaces of the liner. However, the manner in which fiberglass layers are used can result in problems, since the polymer concrete may not readily permeate the fiberglass, resulting in exposed fiberglass on either the inner or outer surface of the liner. This condition adversely affects the physical properties of the resulting laminate part, such as strength and modulus. It can also result in a loss of corrosion resistance, increased friction between the fluid and the liner, and reduced flow rate of the fluid through the passage.